I really like Zotero. The more I use it, the more useful and powerful I find it. Also, the technical support for the product (from the community of users and especially from Dan Stillman is outstanding.
Dan pointed out a really useful feature to me today. When adding items to Zotero, sometimes the title of the item is published ALL IN UPPER CASE or sometimes In A Mixture Of Upper And Lower Case (i.e., title case). It is really tedious to fix by hand; but there is a better way. In viewing mode (that’s in the right-hand-side panel), right-click on the title and choose “Transform text→lower case”. It can then be quickly tweaked to be sentence case.